What is it?
zeit·geist | Pronunciation: 'tsIt-"gIst, 'zIt | Function: noun | Etymology: German, from Zeit (time) + Geist (spirit) | Date: 1884 | Meaning: the general intellectual, moral, and cultural climate of an era
In Google's reality, it is a place where they list their most popular queries, or as they put it, "Search patterns, trends, and surprises according to Google". Check it out. Some interesting things pop up there.